Project Summary Smartphones bring tremendous new opportunities to collect data. These technologies offer capabilities that allow researchers to overcome many limitations and weaknesses in prior modes of data collection. However, smartphone data collection has distinct challenges that other data collection modes do not, particularly for deploying cognitive assessments, which requires stricter standardization than administration of survey questions. Challenges include participants using their own devices, data security, development costs, participant engagement, and representative study populations. Researchers have used surveys, interviews, and diagnostic assessments for decades, but with mobile device research, most of the approaches have not yet been codified and shared. Many high quality solutions exist, but researchers have independently developed these procedures, sometimes with duplication of effort and without interoperability beyond a single team. For conducting research with mobile devices, the field of cognitive aging research urgently needs a model platform that integrates the tremendous innovations in the field over the past decade and provides a unified solution to the research community. The Technical Core delivers this solution through the following aims. Aim 1: Augment an existing Android app and build an iOS app that permits researchers to a conduct a variety of cognitive tests (both graphical and text-based), securely store responses from participants, and securely transmit responses to a data infrastructure for processing, analysis, and distribution. Aim 2: Build upon an existing infrastructure to develop a system that administers smartphone data collection, aggregates and prepares datasets, and allows researchers to query datasets in real time or download data for analysis. Smartphone data collection administration includes receiving responses from devices as well as pushing out new measures to participants' devices in response to previous responses. Aim 3: Execute an operation plan for running and maintaining this integrated smartphone and data infrastructure system. This plan includes procedures for handling routine maintenance, backups, and unexpected events (network or hardware failures). The operation plan will support not only the research project outlined in this proposal, but it is also designed to be a platform for projects from other researchers in the cognitive aging field. The significance of this Technical Core is that it synthesizes many of the innovative solutions cognitive aging researchers have developed to use mobile devices in research, and it makes these solutions available to the entire research community. The innovation is that these solutions are open, flexible, and user-centered: these features maximize engagement from both researchers and study participants. The impact upon the field is through the deliverable product: a suite of mobile apps and robust server software for conducting cognitive aging research.